1. Field of the Invention
The present invention relates to a hermetic compressor, and more particularly to a hermetic compressor capable of reducing the generation of noise by virtue of an improved structure of a valve unit.
2. Description of the Related Art
In general, a hermetic compressor is a device wherein a piston reciprocates inside a cylinder in accordance with rotation of a rotating shaft, thereby serving to compress a refrigerant entering into the cylinder, and to discharge the compressed refrigerant. Such a hermetic compressor basically comprises a compressing unit adapted to compress a refrigerant, and a driving unit adapted to drive the compressing unit.
The compressing unit includes a cylinder defining a compression chamber therein, and a piston reciprocating inside the compression chamber of the cylinder. The compressing unit also includes a cylinder head, which is arranged at one side of the cylinder, and internally defines a suction chamber in communication with the outside, and a discharge chamber. Between the cylinder and cylinder head is interposed a valve unit, which controls the admission and discharge of a refrigerant.
The valve unit includes a valve plate formed with a suction port and discharge port, which provide communication between the cylinder and the respective suction chamber and discharge chamber of the cylinder head, respectively. The valve unit also includes a suction valve for opening or closing the suction port, a discharge valve for opening or closing the discharge port, and a stopper for restricting a maximum opening degree of the discharge valve.
With such a configuration, when the pressure of a refrigerant inside the cylinder is raised beyond the interior pressure of the discharge chamber defined in the cylinder head due to a compression operation of the piston, the discharge valve is opened, thereby allowing the refrigerant in the cylinder to be discharged into the discharge chamber of the cylinder head. Thereafter, when the pressure of the refrigerant inside the cylinder is lowered below the interior pressure of the discharge chamber, the discharge valve is elastically restored, thereby serving to close the discharge port.
Such a conventional hermetic compressor, however, has a problem in that, when discharging the refrigerant, the discharge valve is abruptly opened due to the pressure of the refrigerant, thereby generating vibration and noise as it collides with the stopper. When the discharge valve closes the discharge port, further, the discharge valve collides with the valve plate due to an elastic restoration force thereof, resulting in generation of excessive noise.